First contact
A series with Spock and Pike would have the unique opportunity to have the first word on a variety of races in the Star Trek universe. Discovery did it first with a mix of new (Kelpians, for example) and old races (Klingons, Tellarites and Vulcans, etc), but this series would have the ability to put its own spin on things.
Discovery re-imagined the Klingons, and it wasn’t the first series to do so as TOS Klingons changed by the movies, and changed again through the years.
A Spock and Pike series could lay the groundwork for the first formal relations with the Cardassians, for example. They are a complicated race with whom relations devolved into war, but nothing is known yet about how the Federation and Cardassians first encountered each other.
Perhaps an incident incited the animosity, or maybe their cultural differences were simply too much to overcome. Either way, this series would have the opportunity to tell the story in its own way, and its a race that would require no re-imagining.
Character development
Doctor Boyce, anyone? The doctor in Captain Pike’s first appearance, The Cage, Doctor Boyce has existed in virtual exile from the fandom’s memory for decades.
Boyce gave Pike advice when he was down, poured him a drink on a house visit to his quarters. There was a deep offscreen relationship between these two, and the character could be an essential addition to the group.
Whether it be Boyce, Cadet Thira Sidhu (introduced in the Short Trek “Ask Not”) or other characters, this series would have the chance to do something Discovery has not done especially well through two seasons: Develop its secondary characters.